Identifying stored data slices during a slice migration activity in a dispersed storage network

ABSTRACT

A method for execution by a dispersed storage and task (DST) execution unit includes obtaining a list slice request. At least one other storage unit affiliated with a DSN address range of the list slice request is identified and at least one proxied list slice request is issued to the at least one other storage unit. At least one received proxied list slice response associated with the list slice request is selected, and a list slice response is issued to the requesting entity based on the at least one selected proxied list slice response and locally stored encoded data slices associated with the list slice request.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. § 120 as a continuation-in-part of U.S. Utility applicationSer. No. 15/075,946, entitled “RE-ENCODING DATA IN A DISPERSED STORAGENETWORK”, filed Mar. 21, 2016, which claims priority pursuant to 35U.S.C. § 119(e) to U.S. Provisional Application No. 62/168,114, entitled“RE-ENCODING DATA IN A DISPERSED STORAGE NETWORK”, filed May 29, 2015,both of which are hereby incorporated herein by reference in theirentirety and made part of the present U.S. Utility Patent Applicationfor all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION

Technical Field of the Invention

This invention relates generally to computer networks and moreparticularly to dispersing error encoded data.

Description of Related Art

Computing devices are known to communicate data, process data, and/orstore data. Such computing devices range from wireless smart phones,laptops, tablets, personal computers (PC), work stations, and video gamedevices, to data centers that support millions of web searches, stocktrades, or on-line purchases every day. In general, a computing deviceincludes a central processing unit (CPU), a memory system, userinput/output interfaces, peripheral device interfaces, and aninterconnecting bus structure.

As is further known, a computer may effectively extend its CPU by using“cloud computing” to perform one or more computing functions (e.g., aservice, an application, an algorithm, an arithmetic logic function,etc.) on behalf of the computer. Further, for large services,applications, and/or functions, cloud computing may be performed bymultiple cloud computing resources in a distributed manner to improvethe response time for completion of the service, application, and/orfunction. For example, Hadoop is an open source software framework thatsupports distributed applications enabling application execution bythousands of computers.

In addition to cloud computing, a computer may use “cloud storage” aspart of its memory system. As is known, cloud storage enables a user,via its computer, to store files, applications, etc. on an Internetstorage system. The Internet storage system may include a RAID(redundant array of independent disks) system and/or a dispersed storagesystem that uses an error correction scheme to encode data for storage.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an embodiment of a dispersed ordistributed storage network (DSN) in accordance with the presentinvention;

FIG. 2 is a schematic block diagram of an embodiment of a computing corein accordance with the present invention;

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data in accordance with the present invention;

FIG. 4 is a schematic block diagram of a generic example of an errorencoding function in accordance with the present invention;

FIG. 5 is a schematic block diagram of a specific example of an errorencoding function in accordance with the present invention;

FIG. 6 is a schematic block diagram of an example of a slice name of anencoded data slice (EDS) in accordance with the present invention;

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of data in accordance with the present invention;

FIG. 8 is a schematic block diagram of a generic example of an errordecoding function in accordance with the present invention;

FIG. 9 is a schematic block diagram of an embodiment of a dispersed ordistributed storage network (DSN) in accordance with the presentinvention; and

FIG. 10 is a schematic block diagram of an embodiment of a decentralizedagreement module in accordance with the present invention; and

FIG. 11 is a logic diagram of an example of a method of identifyingstored data slices during a slice migration activity in accordance withthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram of an embodiment of a dispersed, ordistributed, storage network (DSN) 10 that includes a plurality ofcomputing devices 12-16, a managing unit 18, an integrity processingunit 20, and a DSN memory 22. The components of the DSN 10 are coupledto a network 24, which may include one or more wireless and/or wirelined communication systems; one or more non-public intranet systemsand/or public internet systems; and/or one or more local area networks(LAN) and/or wide area networks (WAN).

The DSN memory 22 includes a plurality of storage units 36 that may belocated at geographically different sites (e.g., one in Chicago, one inMilwaukee, etc.), at a common site, or a combination thereof. Forexample, if the DSN memory 22 includes eight storage units 36, eachstorage unit is located at a different site. As another example, if theDSN memory 22 includes eight storage units 36, all eight storage unitsare located at the same site. As yet another example, if the DSN memory22 includes eight storage units 36, a first pair of storage units are ata first common site, a second pair of storage units are at a secondcommon site, a third pair of storage units are at a third common site,and a fourth pair of storage units are at a fourth common site. Notethat a DSN memory 22 may include more or less than eight storage units36. Further note that each storage unit 36 includes a computing core (asshown in FIG. 2, or components thereof) and a plurality of memorydevices for storing dispersed error encoded data.

In various embodiments, each of the storage units operates as adistributed storage and task (DST) execution unit, and is operable tostore dispersed error encoded data and/or to execute, in a distributedmanner, one or more tasks on data. The tasks may be a simple function(e.g., a mathematical function, a logic function, an identify function,a find function, a search engine function, a replace function, etc.), acomplex function (e.g., compression, human and/or computer languagetranslation, text-to-voice conversion, voice-to-text conversion, etc.),multiple simple and/or complex functions, one or more algorithms, one ormore applications, etc. Hereafter, a storage unit may be interchangeablyreferred to as a dispersed storage and task (DST) execution unit and aset of storage units may be interchangeably referred to as a set of DSTexecution units.

Each of the computing devices 12-16, the managing unit 18, and theintegrity processing unit 20 include a computing core 26, which includesnetwork interfaces 30-33. Computing devices 12-16 may each be a portablecomputing device and/or a fixed computing device. A portable computingdevice may be a social networking device, a gaming device, a cell phone,a smart phone, a digital assistant, a digital music player, a digitalvideo player, a laptop computer, a handheld computer, a tablet, a videogame controller, and/or any other portable device that includes acomputing core. A fixed computing device may be a computer (PC), acomputer server, a cable set-top box, a satellite receiver, a televisionset, a printer, a fax machine, home entertainment equipment, a videogame console, and/or any type of home or office computing equipment.Note that each managing unit 18 and the integrity processing unit 20 maybe separate computing devices, may be a common computing device, and/ormay be integrated into one or more of the computing devices 12-16 and/orinto one or more of the storage units 36. In various embodiments,computing devices 12-16 can include user devices and/or can be utilizedby a requesting entity generating access requests, which can includerequests to read or write data to storage units in the DSN.

Each interface 30, 32, and 33 includes software and hardware to supportone or more communication links via the network 24 indirectly and/ordirectly. For example, interface 30 supports a communication link (e.g.,wired, wireless, direct, via a LAN, via the network 24, etc.) betweencomputing devices 14 and 16. As another example, interface 32 supportscommunication links (e.g., a wired connection, a wireless connection, aLAN connection, and/or any other type of connection to/from the network24) between computing devices 12 & 16 and the DSN memory 22. As yetanother example, interface 33 supports a communication link for each ofthe managing unit 18 and the integrity processing unit 20 to the network24.

Computing devices 12 and 16 include a dispersed storage (DS) clientmodule 34, which enables the computing device to dispersed storage errorencode and decode data as subsequently described with reference to oneor more of FIGS. 3-8. In this example embodiment, computing device 16functions as a dispersed storage processing agent for computing device14. In this role, computing device 16 dispersed storage error encodesand decodes data on behalf of computing device 14. With the use ofdispersed storage error encoding and decoding, the DSN 10 is tolerant ofa significant number of storage unit failures (the number of failures isbased on parameters of the dispersed storage error encoding function)without loss of data and without the need for a redundant or backupcopies of the data. Further, the DSN 10 stores data for an indefiniteperiod of time without data loss and in a secure manner (e.g., thesystem is very resistant to unauthorized attempts at accessing thedata).

In operation, the managing unit 18 performs DS management services. Forexample, the managing unit 18 establishes distributed data storageparameters (e.g., vault creation, distributed storage parameters,security parameters, billing information, user profile information,etc.) for computing devices 12-14 individually or as part of a group ofuser devices. As a specific example, the managing unit 18 coordinatescreation of a vault (e.g., a virtual memory block associated with aportion of an overall namespace of the DSN) within the DSN memory 22 fora user device, a group of devices, or for public access and establishesper vault dispersed storage (DS) error encoding parameters for a vault.The managing unit 18 facilitates storage of DS error encoding parametersfor each vault by updating registry information of the DSN 10, where theregistry information may be stored in the DSN memory 22, a computingdevice 12-16, the managing unit 18, and/or the integrity processing unit20.

The DSN managing unit 18 creates and stores user profile information(e.g., an access control list (ACL)) in local memory and/or withinmemory of the DSN memory 22. The user profile information includesauthentication information, permissions, and/or the security parameters.The security parameters may include encryption/decryption scheme, one ormore encryption keys, key generation scheme, and/or dataencoding/decoding scheme.

The DSN managing unit 18 creates billing information for a particularuser, a user group, a vault access, public vault access, etc. Forinstance, the DSN managing unit 18 tracks the number of times a useraccesses a non-public vault and/or public vaults, which can be used togenerate a per-access billing information. In another instance, the DSNmanaging unit 18 tracks the amount of data stored and/or retrieved by auser device and/or a user group, which can be used to generate aper-data-amount billing information.

As another example, the managing unit 18 performs network operations,network administration, and/or network maintenance. Network operationsincludes authenticating user data allocation requests (e.g., read and/orwrite requests), managing creation of vaults, establishingauthentication credentials for user devices, adding/deleting components(e.g., user devices, storage units, and/or computing devices with a DSclient module 34) to/from the DSN 10, and/or establishing authenticationcredentials for the storage units 36. Network administration includesmonitoring devices and/or units for failures, maintaining vaultinformation, determining device and/or unit activation status,determining device and/or unit loading, and/or determining any othersystem level operation that affects the performance level of the DSN 10.Network maintenance includes facilitating replacing, upgrading,repairing, and/or expanding a device and/or unit of the DSN 10.

The integrity processing unit 20 performs rebuilding of ‘bad’ or missingencoded data slices. At a high level, the integrity processing unit 20performs rebuilding by periodically attempting to retrieve/list encodeddata slices, and/or slice names of the encoded data slices, from the DSNmemory 22. For retrieved encoded slices, they are checked for errors dueto data corruption, outdated version, etc. If a slice includes an error,it is flagged as a ‘bad’ slice. For encoded data slices that were notreceived and/or not listed, they are flagged as missing slices. Badand/or missing slices are subsequently rebuilt using other retrievedencoded data slices that are deemed to be good slices to produce rebuiltslices. The rebuilt slices are stored in the DSN memory 22.

FIG. 2 is a schematic block diagram of an embodiment of a computing core26 that includes a processing module 50, a memory controller 52, mainmemory 54, a video graphics processing unit 55, an input/output (IO)controller 56, a peripheral component interconnect (PCI) interface 58,an IO interface module 60, at least one IO device interface module 62, aread only memory (ROM) basic input output system (BIOS) 64, and one ormore memory interface modules. The one or more memory interfacemodule(s) includes one or more of a universal serial bus (USB) interfacemodule 66, a host bus adapter (HBA) interface module 68, a networkinterface module 70, a flash interface module 72, a hard drive interfacemodule 74, and a DSN interface module 76.

The DSN interface module 76 functions to mimic a conventional operatingsystem (OS) file system interface (e.g., network file system (NFS),flash file system (FFS), disk file system (DFS), file transfer protocol(FTP), web-based distributed authoring and versioning (WebDAV), etc.)and/or a block memory interface (e.g., small computer system interface(SCSI), internet small computer system interface (iSCSI), etc.). The DSNinterface module 76 and/or the network interface module 70 may functionas one or more of the interface 30-33 of FIG. 1. Note that the IO deviceinterface module 62 and/or the memory interface modules 66-76 may becollectively or individually referred to as IO ports.

FIG. 3 is a schematic block diagram of an example of dispersed storageerror encoding of data. When a computing device 12 or 16 has data tostore it disperse storage error encodes the data in accordance with adispersed storage error encoding process based on dispersed storageerror encoding parameters. Here, the computing device stores data object40, which can include a file (e.g., text, video, audio, etc.), or otherdata arrangement. The dispersed storage error encoding parametersinclude an encoding function (e.g., information dispersal algorithm(IDA), Reed-Solomon, Cauchy Reed-Solomon, systematic encoding,non-systematic encoding, on-line codes, etc.), a data segmentingprotocol (e.g., data segment size, fixed, variable, etc.), and per datasegment encoding values. The per data segment encoding values include atotal, or pillar width, number (T) of encoded data slices per encodingof a data segment i.e., in a set of encoded data slices); a decodethreshold number (D) of encoded data slices of a set of encoded dataslices that are needed to recover the data segment; a read thresholdnumber (R) of encoded data slices to indicate a number of encoded dataslices per set to be read from storage for decoding of the data segment;and/or a write threshold number (W) to indicate a number of encoded dataslices per set that must be accurately stored before the encoded datasegment is deemed to have been properly stored. The dispersed storageerror encoding parameters may further include slicing information (e.g.,the number of encoded data slices that will be created for each datasegment) and/or slice security information (e.g., per encoded data sliceencryption, compression, integrity checksum, etc.).

In the present example, Cauchy Reed-Solomon has been selected as theencoding function (a generic example is shown in FIG. 4 and a specificexample is shown in FIG. 5); the data segmenting protocol is to dividethe data object into fixed sized data segments; and the per data segmentencoding values include: a pillar width of 5, a decode threshold of 3, aread threshold of 4, and a write threshold of 4. In accordance with thedata segmenting protocol, the computing device 12 or 16 divides dataobject 40 into a plurality of fixed sized data segments (e.g., 1 throughY of a fixed size in range of Kilo-bytes to Tera-bytes or more). Thenumber of data segments created is dependent of the size of the data andthe data segmenting protocol.

The computing device 12 or 16 then disperse storage error encodes a datasegment using the selected encoding function (e.g., Cauchy Reed-Solomon)to produce a set of encoded data slices. FIG. 4 illustrates a genericCauchy Reed-Solomon encoding function, which includes an encoding matrix(EM), a data matrix (DM), and a coded matrix (CM). The size of theencoding matrix (EM) is dependent on the pillar width number (T) and thedecode threshold number (D) of selected per data segment encodingvalues. To produce the data matrix (DM), the data segment is dividedinto a plurality of data blocks and the data blocks are arranged into Dnumber of rows with Z data blocks per row. Note that Z is a function ofthe number of data blocks created from the data segment and the decodethreshold number (D). The coded matrix is produced by matrix multiplyingthe data matrix by the encoding matrix.

FIG. 5 illustrates a specific example of Cauchy Reed-Solomon encodingwith a pillar number (T) of five and decode threshold number of three.In this example, a first data segment is divided into twelve data blocks(D1-D12). The coded matrix includes five rows of coded data blocks,where the first row of X11-X14 corresponds to a first encoded data slice(EDS 1_1), the second row of X21-X24 corresponds to a second encodeddata slice (EDS 2_1), the third row of X31-X34 corresponds to a thirdencoded data slice (EDS 3_1), the fourth row of X41-X44 corresponds to afourth encoded data slice (EDS 4_1), and the fifth row of X51-X54corresponds to a fifth encoded data slice (EDS 5_1). Note that thesecond number of the EDS designation corresponds to the data segmentnumber.

Returning to the discussion of FIG. 3, the computing device also createsa slice name (SN) for each encoded data slice (EDS) in the set ofencoded data slices. A typical format for a slice name 80 is shown inFIG. 6. As shown, the slice name (SN) 80 includes a pillar number of theencoded data slice (e.g., one of 1-T), a data segment number (e.g., oneof 1-Y), a vault identifier (ID), a data object identifier (ID), and mayfurther include revision level information of the encoded data slices.The slice name functions as, at least part of, a DSN address for theencoded data slice for storage and retrieval from the DSN memory 22.

As a result of encoding, the computing device 12 or 16 produces aplurality of sets of encoded data slices, which are provided with theirrespective slice names to the storage units for storage. As shown, thefirst set of encoded data slices includes EDS 1_1 through EDS 5_1 andthe first set of slice names includes SN 1_1 through SN 5_1 and the lastset of encoded data slices includes EDS 1_Y through EDS 5_Y and the lastset of slice names includes SN 1_Y through SN 5_Y.

FIG. 7 is a schematic block diagram of an example of dispersed storageerror decoding of a data object that was dispersed storage error encodedand stored in the example of FIG. 4. In this example, the computingdevice 12 or 16 retrieves from the storage units at least the decodethreshold number of encoded data slices per data segment. As a specificexample, the computing device retrieves a read threshold number ofencoded data slices.

To recover a data segment from a decode threshold number of encoded dataslices, the computing device uses a decoding function as shown in FIG.8. As shown, the decoding function is essentially an inverse of theencoding function of FIG. 4. The coded matrix includes a decodethreshold number of rows (e.g., three in this example) and the decodingmatrix in an inversion of the encoding matrix that includes thecorresponding rows of the coded matrix. For example, if the coded matrixincludes rows 1, 2, and 4, the encoding matrix is reduced to rows 1, 2,and 4, and then inverted to produce the decoding matrix.

FIG. 9 is a schematic block diagram of another embodiment of a dispersedstorage network (DSN) that includes the integrity processing unit 20 ofFIG. 1, the network 24 of FIG. 1, and a plurality of storage sets 1-S.The integrity processing unit 20 includes a decentralized agreementmodule 460 and the DS client module 34 of FIG. 1. The decentralizedagreement module 460 may be implemented utilizing the decentralizedagreement module of FIG. 11. Each storage set includes a set of nstorage units, which can be implemented utilizing the storage unit 36 ofFIG. 1. The storage units can be utilized as distributed storage andtask (DST) execution unit as described previously, and may hereafter beinterchangeably referred to as DST execution (EX) units. Each DSTexecution unit includes the decentralized agreement module 460, the DSclient module 34 of FIG. 1, and memory 88, which can be implementedutilizing main memory 54 of FIG. 2. The DSN functions to identify storedencoded data slices during a slice migration activity.

In a DSN memory that is modified, for example, where new storage unitsare added or removed, or where existing storage units have shrunk orexpanded in capacity, a change to the resource map may be triggered, andcorrespondingly the decentralized agreement protocol (DAP) will remapsome slices to other storage units. However, the change in the DAP doesnot immediately change where the slices are stored. Instead a transfer(migration) of some slices from one location in one storage unit to oneor more new storage units is required before all slices are located inlocations defined by the newly modified resource map and DAP. Duringthis time, while slices are in transit, rebuilding may be complicated asthe exact location of slices is not known. For example, half of thewidth of some slices may reside at their old locations, while the otherhalf may have already moved, and neither side has a threshold.

To accommodate reads and writes, proxying from the old location to thenew location can be done even if the slice is not present. However,listing requests (which are necessary to determine what data is missingand needs to be rebuilt) are complicated by such a migration. To supportfull listing results, and enable rebuilding of data that is beingmigrated, storage units that receive listing requests must perform twolists. The first against their own set of slices still in theirpossession, and then a second list request, against the storage unitthat this storage unit has been migrating to (in accordance with theresource map change). The response from the other storage unit that isbeing migrated to, however, must be filtered, as all the slices held bythat “destination storage unit” may not all have previously belonged tothe storage unit (“the source storage unit”) that sent the listingrequest. The source unit must then apply the DAP to all names returnedin the listing response from the destination storage unit to filter outall names except for those that would have belonged to this ds unitaccording to the previous resource map and DAP.

In an example of operation of the identifying of the stored encoded dataslices 462 during the slice migration activity, a storage unit of thestorage set 1 receives, via the network 24, a list slice request fromthe integrity processing unit 20, where the slice migration activityincludes the set of storage units of storage set 1 transferring encodeddata slices to storage units of the storage set 2 in accordance withpending location weight changes (e.g., weighting factors of adecentralized agreement protocol function). The list slice requestincludes a slice name range in accordance with current weightingfactors, where the decentralized agreement module 460 of the integrityprocessing unit 20 performs the decentralized agreement protocolfunction on a DSN address of the slice name range utilizing the currentweighting factors to determine that the DSN address has been associatedwith the storage set 1.

Having obtained the list slice request, the storage unit can identifyone or more other storage units affiliated with the slice name range,where the one or more storage units are associated with the slicemigration activity. For example, the storage unit can utilize thedecentralized agreement module 460 to perform a decentralized agreementprotocol function on a DSN address of the list slice request, utilizingpending weighting factors to identify the one or more other storageunits.

Having identified the one or more other storage units, the storage unitcan issue, via the network 24, a proxied list slice request to theidentified one or more other storage units. The issuing can includegenerating proxied list slice requests to include a DSN address range inaccordance with one or more of the list slice request and/or a DSNaddress range affiliated with the pending weighting factors.

The storage unit can select received proxied list slice responsesassociated with the list slice request. The one or more other storageunits can send the proxied list slice responses in response to theproxied list slice request, and each proxied list slice response caninclude a list of slice names associated with the DSN address range ofthe pending weighting factors stored in the memory 88 of the storageunits sending the proxied list slice response. The selecting can includeperforming the decentralized agreement protocol function on a slice nameof the received proxied list slice response by using the currentweighting factors to produce scores and identifying responses associatedwith a highest score for the storage unit.

Having selected the received proxied list slice responses, the DS clientmodule 34 of the storage unit can issue, via the network 24, a listslice response to the requesting entity, such as the integrityprocessing unit 20, based on the selected list slice responses andlocally stored encoded data slices associated with the list slicerequest. For example, the storage unit can identify locally storedencoded data slices, and can generate the list slice response to includeslice names of the locally stored encoded data slices and/or slice namesof the selected list slice responses.

In various embodiments, a processing system of a dispersed storage andtask (DST) execution unit includes at least one processor and a memorythat stores operational instructions, that when executed by the at leastone processor cause the processing system to obtain a list slice. Atleast one other storage unit affiliated with a DSN address range of thelist slice request is identified and at least one proxied list slicerequest is issued to the at least one other storage unit. At least onereceived proxied list slice response associated with the list slicerequest is selected, and a list slice response is issued to therequesting entity based on the at least one selected proxied list sliceresponse and locally stored encoded data slices associated with the listslice request.

In various embodiments, the list slice request is received from anintegrity processing unit via a network. In various embodiments, theintegrity processing unit issues the list slice request in response todetermining that the DSN address range of the list slice request isassociated with a first storage unit set involved in an ongoing slicemigration activity, and wherein the ongoing slice migration activityincludes an ongoing transfer of encoded slices from the first storageunit set to a second storage unit set. In various embodiments, theongoing slice migration activity corresponds to a pending change ofweighting factors of a decentralized agreement protocol function. Invarious embodiments, the at least one other storage unit is identifiedin response to determining that it is associated with the ongoing slicemigration activity.

In various embodiments, the at least one other storage unit isidentified by performing a decentralized agreement protocol on a DSNaddress of the list slice request based on pending weighting factors. Invarious embodiments, at least one proxied list slice request isgenerated to include a DSN address range based on at least one of: thelist slice request or a DSN address range affiliated with pendingweighting factors. In various embodiments, a plurality of proxied listslice responses are received that include a plurality of slice names. Aplurality of scores corresponding to the plurality of proxied list sliceresponses are generated by performing a decentralized agreement protocolfunction on the plurality of slice names by utilizing current weightingfactors. The at least one received proxied list slice response isselected based on the plurality of scores. In various embodiments, ahighest score of the plurality of scores is identified, and the at leastone selected proxied list slice response corresponds to the highestscore. In various embodiments, the list slice response is generated toinclude slice names of the locally stored encoded data slices and slicenames of the at least one selected proxied list slice response.

FIG. 10 is a schematic block diagram of an embodiment of a decentralizedagreement module, such as the decentralized agreement module 460 of FIG.9, that includes a set of deterministic functions 1-N, a set ofnormalizing functions 1-N, a set of scoring functions 1-N, and a rankingfunction. Each of the deterministic function, the normalizing function,the scoring function, and the ranking function, may be implementedutilizing the processing module 50 of the computing core 26 of FIG. 2.The decentralized agreement module may be implemented utilizing anymodule and/or unit of a dispersed storage network (DSN). For example,the decentralized agreement module is implemented utilizing the DSclient module 34 of FIG. 1.

The decentralized agreement module functions to receive a ranked scoringinformation request and to generate ranked scoring information based onthe ranked scoring information request and other information. The rankedscoring information request includes one or more of an asset identifier(ID) of an asset associated with the request, an asset type indicator,one or more location identifiers of locations associated with the DSN,one or more corresponding location weights, and a requesting entity ID.The asset includes any portion of data associated with the DSN includingone or more asset types including a data object, a data record, anencoded data slice, a data segment, a set of encoded data slices, and aplurality of sets of encoded data slices. As such, the asset ID of theasset includes one or more of a data name, a data record identifier, asource name, a slice name, and a plurality of sets of slice names.

Each location of the DSN includes an aspect of a DSN resource. Examplesof locations includes one or more of a storage unit, a memory device ofthe storage unit, a site, a storage pool of storage units, a pillarindex associated with each encoded data slice of a set of encoded dataslices generated by an information dispersal algorithm (IDA), a DSclient module 34 of FIG. 1, a computing device 16 of FIG. 1, anintegrity processing unit 20 of FIG. 1, a managing unit 18 of FIG. 1, acomputing device 12 of FIG. 1, and a computing device 14 of FIG. 1.

Each location is associated with a location weight based on one or moreof a resource prioritization of utilization scheme and physicalconfiguration of the DSN. The location weight includes an arbitrary biaswhich adjusts a proportion of selections to an associated location suchthat a probability that an asset will be mapped to that location isequal to the location weight divided by a sum of all location weightsfor all locations of comparison. For example, each storage pool of aplurality of storage pools is associated with a location weight based onstorage capacity. For instance, storage pools with more storage capacityare associated with higher location weights than others. The otherinformation may include a set of location identifiers and a set oflocation weights associated with the set of location identifiers. Forexample, the other information includes location identifiers andlocation weights associated with a set of memory devices of a storageunit when the requesting entity utilizes the decentralized agreementmodule to produce ranked scoring information with regards to selectionof a memory device of the set of memory devices for accessing aparticular encoded data slice (e.g., where the asset ID includes a slicename of the particular encoded data slice).

The decentralized agreement module outputs substantially identicalranked scoring information for each ranked scoring information requestthat includes substantially identical content of the ranked scoringinformation request. For example, a first requesting entity issues afirst ranked scoring information request to the decentralized agreementmodule and receives first ranked scoring information. A secondrequesting entity issues a second ranked scoring information request tothe decentralized agreement module and receives second ranked scoringinformation. The second ranked scoring information is substantially thesame as the first ranked scoring information when the second rankedscoring information request is substantially the same as the firstranked scoring information request.

As such, two or more requesting entities may utilize the decentralizedagreement module to determine substantially identical ranked scoringinformation. As a specific example, the first requesting entity selectsa first storage pool of a plurality of storage pools for storing a setof encoded data slices utilizing the decentralized agreement module andthe second requesting entity identifies the first storage pool of theplurality of storage pools for retrieving the set of encoded data slicesutilizing the decentralized agreement module.

In an example of operation, the decentralized agreement module receivesthe ranked scoring information request. Each deterministic functionperforms a deterministic function on a combination and/or concatenation(e.g., add, append, interleave) of the asset ID of the request and anassociated location ID of the set of location IDs to produce an interimresult. The deterministic function includes at least one of a hashingfunction, a hash-based message authentication code function, a maskgenerating function, a cyclic redundancy code function, hashing moduleof a number of locations, consistent hashing, rendezvous hashing, and asponge function. As a specific example, deterministic function 2 appendsa location ID 2 of a storage pool 2 to a source name as the asset ID toproduce a combined value and performs the mask generating function onthe combined value to produce interim result 2.

With a set of interim results 1-N, each normalizing function performs anormalizing function on a corresponding interim result to produce acorresponding normalized interim result. The performing of thenormalizing function includes dividing the interim result by a number ofpossible permutations of the output of the deterministic function toproduce the normalized interim result. For example, normalizing function2 performs the normalizing function on the interim result 2 to produce anormalized interim result 2.

With a set of normalized interim results 1-N, each scoring functionperforms a scoring function on a corresponding normalized interim resultto produce a corresponding score. The performing of the scoring functionincludes dividing an associated location weight by a negative log of thenormalized interim result. For example, scoring function 2 divideslocation weight 2 of the storage pool 2 (e.g., associated with locationID 2) by a negative log of the normalized interim result 2 to produce ascore 2.

With a set of scores 1-N, the ranking function performs a rankingfunction on the set of scores 1-N to generate the ranked scoringinformation. The ranking function includes rank ordering each score withother scores of the set of scores 1-N, where a highest score is rankedfirst. As such, a location associated with the highest score may beconsidered a highest priority location for resource utilization (e.g.,accessing, storing, retrieving, etc., the given asset of the request).Having generated the ranked scoring information, the decentralizedagreement module outputs the ranked scoring information to therequesting entity.

FIG. 11 is a flowchart illustrating an example of identifying storeddata slices during a slice migration activity. In particular, a methodis presented for use in association with one or more functions andfeatures described in conjunction with FIGS. 1-9, for execution by adispersed storage and task (DST) execution unit that includes aprocessor or via another processing system of a dispersed storagenetwork that includes at least one processor and memory that storesinstruction that configure the processor or processors to perform thesteps described below. Step 1102 includes obtaining a list slicerequest. This can include receiving a list slice request from arequesting entity and/or generating the list slice request based on astorage error detection schedule, a predetermination, etc.

The method continues at step 1104, which includes identifying at leastone other storage unit affiliated with a DSN address range of the listslice request. For example, a decentralized agreement protocol functioncan be performed on the DSN address of the list slice request usingpending weighting factors of the plurality of storage units.

The method continues at step 1106, where at least one proxied list slicerequest is issued to the identified at least one other storage unit. Forexample, the proxied list slice request is generated to include a DSNaddress range in accordance with one or more of the list slice requestand a DSN address range affiliated with the pending weighting factors.

The method continues at step 1108, where at least one received proxiedlist slice response associated with the list slice request is selected.For example, the decentralized agreement protocol function is performedon a slice name of a received proxied list slice response using thecurrent weighting factors to produce scores and identifies responsesassociated with a high score for the storage unit.

The method continues at step 1110, where a list slice response is issuedto a requesting entity based on the selected list slice responses andlocally stored encoded data slices associated with the list slicerequest. For example, the locally stored encoded data slices areidentified, and the list slice response is generated to include slicenames of the locally stored encoded data slices and slice names of theselected list slice responses. The generated list slice response is sentto the requesting entity.

In various embodiments, a non-transitory computer readable storagemedium includes at least one memory section that stores operationalinstructions that, when executed by a processing system of a dispersedstorage network (DSN) that includes a processor and a memory, causes theprocessing system to obtain a list slice request. At least one otherstorage unit affiliated with a DSN address range of the list slicerequest is identified and at least one proxied list slice request isissued to the at least one other storage unit. At least one receivedproxied list slice response associated with the list slice request isselected, and a list slice response is issued to the requesting entitybased on the at least one selected proxied list slice response andlocally stored encoded data slices associated with the list slicerequest.

It is noted that terminologies as may be used herein such as bit stream,stream, signal sequence, etc. (or their equivalents) have been usedinterchangeably to describe digital information whose contentcorresponds to any of a number of desired types (e.g., data, video,speech, audio, etc. any of which may generally be referred to as‘data’).

As may be used herein, the terms “substantially” and “approximately”provides an industry-accepted tolerance for its corresponding termand/or relativity between items. Such an industry-accepted toleranceranges from less than one percent to fifty percent and corresponds to,but is not limited to, component values, integrated circuit processvariations, temperature variations, rise and fall times, and/or thermalnoise. Such relativity between items ranges from a difference of a fewpercent to magnitude differences. As may also be used herein, theterm(s) “configured to”, “operably coupled to”, “coupled to”, and/or“coupling” includes direct coupling between items and/or indirectcoupling between items via an intervening item (e.g., an item includes,but is not limited to, a component, an element, a circuit, and/or amodule) where, for an example of indirect coupling, the intervening itemdoes not modify the information of a signal but may adjust its currentlevel, voltage level, and/or power level. As may further be used herein,inferred coupling (i.e., where one element is coupled to another elementby inference) includes direct and indirect coupling between two items inthe same manner as “coupled to”. As may even further be used herein, theterm “configured to”, “operable to”, “coupled to”, or “operably coupledto” indicates that an item includes one or more of power connections,input(s), output(s), etc., to perform, when activated, one or more itscorresponding functions and may further include inferred coupling to oneor more other items. As may still further be used herein, the term“associated with”, includes direct and/or indirect coupling of separateitems and/or one item being embedded within another item.

As may be used herein, the term “compares favorably”, indicates that acomparison between two or more items, signals, etc., provides a desiredrelationship. For example, when the desired relationship is that signal1 has a greater magnitude than signal 2, a favorable comparison may beachieved when the magnitude of signal 1 is greater than that of signal 2or when the magnitude of signal 2 is less than that of signal 1. As maybe used herein, the term “compares unfavorably”, indicates that acomparison between two or more items, signals, etc., fails to providethe desired relationship.

As may also be used herein, the terms “processing module”, “processingcircuit”, “processor”, and/or “processing unit” may be a singleprocessing device or a plurality of processing devices. Such aprocessing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, and/or processing unit may be, or furtherinclude, memory and/or an integrated memory element, which may be asingle memory device, a plurality of memory devices, and/or embeddedcircuitry of another processing module, module, processing circuit,and/or processing unit. Such a memory device may be a read-only memory,random access memory, volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module,module, processing circuit, and/or processing unit includes more thanone processing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,and/or processing unit implements one or more of its functions via astate machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory and/or memory element storing the correspondingoperational instructions may be embedded within, or external to, thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry. Still further note that, the memoryelement may store, and the processing module, module, processingcircuit, and/or processing unit executes, hard coded and/or operationalinstructions corresponding to at least some of the steps and/orfunctions illustrated in one or more of the Figures. Such a memorydevice or memory element can be included in an article of manufacture.

One or more embodiments have been described above with the aid of methodsteps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claims. Further, the boundariesof these functional building blocks have been arbitrarily defined forconvenience of description. Alternate boundaries could be defined aslong as the certain significant functions are appropriately performed.Similarly, flow diagram blocks may also have been arbitrarily definedherein to illustrate certain significant functionality.

To the extent used, the flow diagram block boundaries and sequence couldhave been defined otherwise and still perform the certain significantfunctionality. Such alternate definitions of both functional buildingblocks and flow diagram blocks and sequences are thus within the scopeand spirit of the claims. One of average skill in the art will alsorecognize that the functional building blocks, and other illustrativeblocks, modules and components herein, can be implemented as illustratedor by discrete components, application specific integrated circuits,processors executing appropriate software and the like or anycombination thereof.

In addition, a flow diagram may include a “start” and/or “continue”indication. The “start” and “continue” indications reflect that thesteps presented can optionally be incorporated in or otherwise used inconjunction with other routines. In this context, “start” indicates thebeginning of the first step presented and may be preceded by otheractivities not specifically shown. Further, the “continue” indicationreflects that the steps presented may be performed multiple times and/ormay be succeeded by other activities not specifically shown. Further,while a flow diagram indicates a particular ordering of steps, otherorderings are likewise possible provided that the principles ofcausality are maintained.

The one or more embodiments are used herein to illustrate one or moreaspects, one or more features, one or more concepts, and/or one or moreexamples. A physical embodiment of an apparatus, an article ofmanufacture, a machine, and/or of a process may include one or more ofthe aspects, features, concepts, examples, etc. described with referenceto one or more of the embodiments discussed herein. Further, from figureto figure, the embodiments may incorporate the same or similarly namedfunctions, steps, modules, etc. that may use the same or differentreference numbers and, as such, the functions, steps, modules, etc. maybe the same or similar functions, steps, modules, etc. or differentones.

Unless specifically stated to the contra, signals to, from, and/orbetween elements in a figure of any of the figures presented herein maybe analog or digital, continuous time or discrete time, and single-endedor differential. For instance, if a signal path is shown as asingle-ended path, it also represents a differential signal path.Similarly, if a signal path is shown as a differential path, it alsorepresents a single-ended signal path. While one or more particulararchitectures are described herein, other architectures can likewise beimplemented that use one or more data buses not expressly shown, directconnectivity between elements, and/or indirect coupling between otherelements as recognized by one of average skill in the art.

The term “module” is used in the description of one or more of theembodiments. A module implements one or more functions via a device suchas a processor or other processing device or other hardware that mayinclude or operate in association with a memory that stores operationalinstructions. A module may operate independently and/or in conjunctionwith software and/or firmware. As also used herein, a module may containone or more sub-modules, each of which may be one or more modules.

As may further be used herein, a computer readable memory includes oneor more memory elements. A memory element may be a separate memorydevice, multiple memory devices, or a set of memory locations within amemory device. Such a memory device may be a read-only memory, randomaccess memory, volatile memory, non-volatile memory, static memory,dynamic memory, flash memory, cache memory, and/or any device thatstores digital information. The memory device may be in a form a solidstate memory, a hard drive memory, cloud memory, thumb drive, servermemory, computing device memory, and/or other physical medium forstoring digital information.

While particular combinations of various functions and features of theone or more embodiments have been expressly described herein, othercombinations of these features and functions are likewise possible. Thepresent disclosure is not limited by the particular examples disclosedherein and expressly incorporates these other combinations.

What is claimed is:
 1. A method for execution by a dispersed storage andtask (DST) execution unit that includes a processor, the methodcomprises: obtaining a first request that includes a slice name range;identifying at least one storage unit affiliated with the slice namerange of the first request; issuing at least one second request to theat least one storage unit that includes a dispersed storage network(DSN) address range associated with the slice name range; receiving atleast one first response from the at least one storage unit in responseto the at least one second request, wherein the at least one firstresponse includes a list of slice names associated with the DSN addressrange; selecting at least one selected first response from the at leastone first response based on the slice name range of the first request;and issuing a second response to a requesting entity that includes slicenames of a list of slice names included in the at least one selectedfirst response that are associated with the slice name range of thefirst request, and that further includes slice names of locally storedencoded data slices that are associated with the slice name range of thefirst request.
 2. The method of claim 1, wherein the first request isreceived from an integrity processing unit via a network.
 3. The methodof claim 2, wherein the integrity processing unit issues the firstrequest in response to determining that the slice name range of thefirst request is associated with a first storage unit set involved in anongoing slice migration activity, and wherein the ongoing slicemigration activity includes an ongoing transfer of encoded slices fromthe first storage unit set to a second storage unit set.
 4. The methodof claim 3, wherein the ongoing slice migration activity corresponds toa pending change of weighting factors of a decentralized agreementprotocol function.
 5. The method of claim 3, wherein the at least onestorage unit is identified in response to determining that it isassociated with the ongoing slice migration activity.
 6. The method ofclaim 1, wherein the at least one storage unit is identified byperforming a decentralized agreement protocol on a DSN address indicatedin the slice name range of the first request based on pending weightingfactors.
 7. The method of claim 1, further comprising: generating the atleast one second request including the DSN address range based on atleast one of: the first request or a DSN address range affiliated withpending weighting factors.
 8. The method of claim 1, further comprising:receiving a plurality of first responses that include a plurality oflists of slice names; and generating a plurality of scores correspondingto the plurality of first responses by performing a decentralizedagreement protocol function on the plurality of slice names by utilizingcurrent weighting factors; wherein the at least one selected firstresponse is selected based on the plurality of scores.
 9. The method ofclaim 8, further comprising: identifying a highest score of theplurality of scores, wherein the at least one selected first responsecorresponds to the highest score.
 10. The method of claim 1, furthercomprising: generating the second response including the slice names ofthe locally stored encoded data slices and the slice names of the atleast one selected first response.
 11. A processing system of adispersed storage and task (DST) execution unit comprises: at least oneprocessor; and a memory that stores operational instructions, that whenexecuted by the at least one processor cause the processing system to:obtain a first request that includes a slice name range; identify atleast one storage unit affiliated with the slice name range of the firstrequest; issue at least one second request to the at least one storageunit that includes a dispersed storage network (DSN) address rangeassociated with the slice name range; receive at least one firstresponse from the at least one storage unit in response to the at leastone second request, wherein the at least one first response includes alist of slice names associated with the DSN address range; select atleast one selected first response from the at least one first responsebased on the slice name range of the first request; and issue a secondresponse to a requesting entity that includes slice names of a list ofslice names included in the at least one selected first response thatare associated with the slice name range of the first request, and thatfurther includes slice names of locally stored encoded data slices thatare associated with the slice name range of the first request.
 12. Theprocessing system of claim 11, wherein the first request is receivedfrom an integrity processing unit via a network.
 13. The processingsystem of claim 12, wherein the integrity processing unit issues thefirst request in response to determining that the slice name range ofthe first request is associated with a first storage unit set involvedin an ongoing slice migration activity, and wherein the ongoing slicemigration activity includes an ongoing transfer of encoded slices fromthe first storage unit set to a second storage unit set.
 14. Theprocessing system of claim 13, wherein the ongoing slice migrationactivity corresponds to a pending change of weighting factors of adecentralized agreement protocol function.
 15. The processing system ofclaim 13, wherein the at least one storage unit is identified inresponse to determining that it is associated with the ongoing slicemigration activity.
 16. The processing system of claim 11, wherein theat least one storage unit is identified by performing a decentralizedagreement protocol on a DSN address indicated in the slice name range ofthe first request based on pending weighting factors.
 17. The processingsystem of claim 11, wherein the operational instructions, when executedby the at least one processor, further cause the processing system to:generate the at least one second request including the DSN address rangebased on at least one of: the first request or a DSN address rangeaffiliated with pending weighting factors.
 18. The processing system ofclaim 11, wherein the operational instructions, when executed by the atleast one processor, further cause the processing system to: receive aplurality of first responses that include a plurality of lists of slicenames; and generate a plurality of scores corresponding to the pluralityof first responses by performing a decentralized agreement protocolfunction on the plurality of slice names by utilizing current weightingfactors; wherein the at least one selected first response is selectedbased on the plurality of scores.
 19. The processing system of claim 18,wherein the operational instructions, when executed by the at least oneprocessor, further cause the processing system to: identify a highestscore of the plurality of scores, wherein the at least one selectedfirst response corresponds to the highest score.
 20. A non-transitorycomputer readable storage medium comprises: at least one memory sectionthat stores operational instructions that, when executed by a processingsystem of a dispersed storage network (DSN) that includes a processorand a memory, causes the processing system to: obtain a first requestthat includes a slice name range; identify at least one storage unitaffiliated with the slice name range of the first request; issue atleast one second request to the at least one storage unit that includesa DSN address range associated with the slice name range; receive atleast one first response from the at least one storage unit in responseto the at least one second request, wherein the at least one firstresponse includes a list of slice names associated with the DSN addressrange; select at least one selected first response from the at least onefirst response based on the slice name range of the first request; andissue a second response to a requesting entity that includes slice namesof a list of slice names included in the at least one selected firstresponse that are associated with the slice name range of the firstrequest, and that further includes slice names of locally stored encodeddata slices that are associated with the slice name range of the firstrequest.